1. Field of the Invention
The present invention relates to a tube pump that employs a flexible tube diaphragm and is suitable for conveying slurry solution and the like.
2. Description of the Related Art
A tube pump with a flexible tube has been known as a pump suitable for conveying liquid. Such the tube pump has a structure, which defines outside and inside of a flexible tube diaphragm as an actuator fluid space and a pump chamber respectively, and which arranges an intake valve at one end portion of the flexible tube diaphragm and an discharge valve at the other end portion thereof. When an actuator fluid is periodically supplied into the actuator fluid space to expand and contract the flexible tube in the radial direction, an object fluid (a fluid to be conveyed) is conveyed by a repetition of suck and discharge of the object fluid into and from the pump chamber. The tube pump conveys a fluid by expanding and contracting the whole sidewall of the flexible tube in the radial direction. Therefore, it can obtain a larger liquid-conveying ability with a smaller size than a conventional diaphragm pump. In addition, unlike the conventional diaphragm pump, as the pump chamber in the tube pump is cylindrical, the object fluid can be conveyed straight. As a result, the tube pump has no part for causing the object solution to stay, thereby being suitable for conveying a slurry solution.
A conventional driving system has, however, a limitation which limits the liquid-conveying ability of the tube pump. In the conventional tube pump, a crankshaft is driven by a motor so as to move reciprocally a piston that is connected to the crankshaft. This motion allows oil to be introduced into and drawn from an oil hydraulic chamber. The introduction and draw of the oil deforms the diaphragm, which in turn deforms the flexible tube through a pressure transmission medium interposed between the diaphragm and the flexible tube. Therefore, a stroke and speed of motion of the piston would limit the liquid-conveying ability of the tube pump.